A Use Case question.

Question

Hello all
I am currently developing an event management assignment for my degree.
A subset of problem statment
Attendee is a person, who would register with the application
in order to view the posted events.
For this part of the problem statment i have identified a usecase
"register attendee".
I will type the use case here. Since i am a novice, I would really like
design gurus to throw some light on the use case and suggest me changes
I will really appreciate it.
Use case : register attendee
Pre-condition: Attendee decides to register.
Main Success Scenario:
     Actor                         System
1. Attendee requests to register.
                    2. Provides registration form.
3. Attendee fills the form and
submits.                     
                    4. System checks for valid
                    authentication.
(//for eg. unique username)
                    5. System validates the information
(//for eg.compulsory fields
                         present or not)
                    6. System notifies through mail.
                    7. Displays registration was
                    successful.
Alternative Flow :
4 a) Invalid authentication : Displays appropriate message.
5 a) Invalid information : Displays appropriate message.
6 a) Mail notification failure : Logs the failure message and email.
Please guide me friends. I am a bit confused.
Thanks in advance.
Jenny               

Answer 1

Use case are pretty good for both of these. You know
your system needs to allow an ATTENDEE to register
with the SYSTEM using a REGISTRATION FORM. These sound
like things that either you need to model (what
attributes do the form and attendee have) or a thing
that you need to build the "system".
The steps in the use case tell you how the system must
behave. It needs to "getRegistrationForm" and give it
the attendee. The Attendee needs to
"completeRegistrationForm" and
"submitRegistrationForm". So, with the authentication
and validation rounding out the process you have a
good idea of what kind of methods you need as a base
in order to deal with the real world concepts you have
identified.I am through with what behaviour my system will need to provide in
order to realize the use case. But I will have to assign the behaviour
appropriately to classes of objects. I would like to go to the design model once i have a good understanding of the domain model. This is where the problem starts, should i identify, AuthenticationVerifier,InformationVerfier as different concepts and give later say AuthenticationVerifier the responsibility of verifying unique authentication and InformationVerfier the responsibility of verifying information received with the form or should I only take one concept of say Administrator that would perform the above two stated behaviours. I understand that it is always good to overspecify concepts rather than under specify but at some point of time i will have to make that decision.
If its a libray system, it is easy to identify certain priliminary concepts say book, patron, etc. as they occupy some physical space. But here nothing is clear. There isn't any entity in my use case, that occupies a physical space that i can easily identify as a real world concept.
My question is, how in this case, do someone define the notion of concept when there is nothing in the main success scenario that occupies space. My use case, only specifies what will be done with the
attendee information, not who will do it. So as a use case developer, am i responsible to map these processes with some physical entities that i have derived for eg. AuthenticationVerfier.
ps. You will need to add the Attendee as an Actor. She
is the one that is initiating the activity.Does it mean that as Attendee is an actor, he/she cannot be a concept?